- Remove and discard excess fat on surface of steak. Slice steak into ⅛ to ¼ inch thick pieces. (Steak can be frozen slightly for 30 minutes to make it easier to slice.) Blot slices dry with paper towel and transfer to 2 large resealable plastic bags.
- Pour Korean BBQ Sauce in one bag and Teriyaki Takumi, Original in the other. Close the bags and use hands to massage sauces evenly around beef. Seal bags and press to remove air. Refrigerate for at least 2 hours or overnight.
- Preheat oven to 175ºF. Drain marinade and remove beef strips from bags. Transfer strips on cooling racks placed on 2 large baking sheets lined with foil. Leave about ½ inch of space between beef strips for air to circulate. Sprinkle teriyaki takumi beef with black pepper and sprinkle Korean BBQ beef with red pepper flakes.
- Bake for 3 ½ -4 hours or until jerky is dry but still pliable. Store jerky in an airtight container in refrigerator.